On a physical sense maybe, but mentally I would say no. But at the end of the day it depends on the person themself.
In the ammy circuit, alot of times when pure bred grapplers transition over to MMA, the mental aspect of striking destroys them. Getting shut down big time against a fairly decent striker with TDD, and its bad. Some actually lose by sub being out their element.
I've seen first hand guys shut down and just think about surviving and not winning after getting cracked by stiff jab in the opening. It screws with you mentally: this fighter's fastest and "weakest" strike just did that much damage, imagine if he/she throw's power shots.
Yeah I think some of the guys are miss interpreting what I wrote. Physical toll on your body, there is no arguing, grappling wears your body down. I'm not saying striking isn't tough, or that its not hard on the body... especially sparring and actual bouts, but the day to day training in Boxing/MT/Karate is very low impact on the body in comparison to your typical jiujitsu gym, especially when its noob vs noob.